The effect of zeolite and cement additives on the mechanical behavior and dispersive index of clay soil

Some natural clay-rich soils are highly erodible by flowing water both at and below the land surface. These soils contain an abundance of clay particles that disperse (slake) and deflocculate when relatively pure water is added. Dispersive soils can cause great damage to various structures, so geotechnical engineers propose different methods to modify and stabilize these types of soils. Chemical stabilization with cement or lime is the most common method to improve the properties of dispersivity and swelling soils. Word environmental problems such as producing large amounts of heat-trapping greenhouse gases for the production of cement or lime made engineers replace them. This paper investigated the effect of replacing part of cement with zeolite (as an environmentally friendly additive) to stabilize a type of clay and the change in dispersivity potential has been evaluated. The results of this study showed that by replacing a part of cement with zeolite, the maximum dry density increases and the optimum moisture decreases, which is a different process compared to cement stabilization. The behavior of the sample in the uniaxial test was influenced by the percentage of replacement of cement with zeolite. The results of the double hydrometer test also showed that the combination of cement and zeolite reduces the potential of soil dispersion. It also observed in the sedimentation experiments that increase in the zeolite ratio, the sedimentation rate increases, which can be justified by the decrease in the thickness of the double layer of clay so confirming decrease the dispersion potential. SEM microstructural analysis also indicated the formation of hydrated calcium silicate gel in the mixture, which improved the mechanical and resistance characteristics and reduced the swelling clay dispersivity potential.